Polymer of vinyl acetylene and process of producing the same



Patented Feb. 7, 1933 UNITED STATES PATENT OFFICE ALBERT S. CARTER, OI WILMINGTON, DELAWARE, AND FREDERICK B. DOWNING, 0] CARNEYS POINT, NEW JERSEY, ASSIGNORS T0 E; I. DU PONT DE NEMOURS & COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE POLYMER OI VINYL AGETYLEJME AND PROCESS OF PRODUCING THE SAME No Drawing.

This invention relates to the polymerization of unsaturated hydrocarbons and to the resulting products, and more particularly relates to the formation'of novel unsaturated carbon has the molecular formula (LH, and

the structure GH CH- C 5 CH. It has also been land Serial No. 305,866, filedSeptember 13, 1928) andby Calcott and Downing (Serial No. 303,494, filed September .1, 1928) by.

polymerizing acetylene in' the presence of a catalyst composed .of a cuprous salt, metallic copper, a salt of a tertiary amine or ammonia, and water and/or suitable acids. Through the agency of this catalytic medium, acetylene is'caused to react with itself to produce vinylacetylene, divinylacetylene and other hydrocarbonsof higher molecular weight. These compounds have been readily separated and purified by simple known means of fractional distillation. The boiling point of vinylacetylene lies between v6 and 10 C.

In these, catalytic processes as described by Nieuwland and Calcott and Downing in the above mentioned applications, the acetylen, activated by means'of the cuprous copper, is

caused to react to form straight chain hydro carbons.

In a subsequent application of Nieuwland (Serial No. 330,415, filed January 4, 1929) La process for polymerizing a mixture containing the above described straight chain hydrocarbons 'is disclosed. The resulting product, however,by reason of the presence of acetylene polymers of various constitution, in part of straight chain structure, is an anon mous olymer mixture.

The 0 ject oi the present invention is the production of substantially pure nonbenzenoid hydrocarbons which (are polymers of vinyl acetylene and have the formula ((LH in which a may be any whole numrepared in small amounts by Nieuw -as well as the great majorit uct from the late Nieuwlan Application tiled December- 19, 1930. Serial No. 503,806.

ber greater than one. A further object is the preparation from acetylene of a hydrocarbon product free from straight chain hydrocarbons.

With these objects in view, we have discovered that if. vinylacet le'ne be polymerized with itself alone and in the absence of a catalyst of the type disclosed by Nieuwland (Serial N 0. 305,866) and composed of a solution of cuprous chloride in the presence of ammonium salts, and preferably with the aid of heat, products of higher molecular weight and of the desired type are produced.

In the present invention, polymerization of vinylacetylene with itself also results in compounds with the formula O H C H etc.,

' has the formula shown as corresponding to the other straight chained members (i. e.-vinyland divinylacetylene), whereas the compound corresponding to the formula (1 H, formed under the claims of the present invention is believed to be Regardless of the explanation, that there is a distinct difference in constitution is established by the fact that the tetramer of acetylene formed by the early Nieuwland process of the prodprocess gives no test for acetlyenic hydrogen with ammoniacal cuprous chloride, whereas all of the non-resinouspolymers formed by the polymerization of vinylacetylene according to the process of this invention, give a yellow acetylide, similar to the yellow cuprous salt or vinylacetylene itself when so reacted.

As will appear below the pure vinylacetylene may be polymerized undera variety of conditions, alone or in solution in an inert solvent and either in the presence or absence product decreases and the boiling point increases with the resulting formation of less volatile material. As the less volatile ortion increases, first'a portion of the pro uct soluble in acetone becomes insoluble in alcohol; thereafter the alcohol insoluble portion increases and a portion of it becomes insoluble in acetone but soluble in benzene; with continued heating, the acetone insoluble portion increases and. a small amount of material is formed which is insoluble in benzene. Following the appearance of this benzene insoluble material, the entire mass becomes semi-solid then gels; at this point, generally 30-60% of the mass is non-volatile. If heating is continued, the gel becomes solid, forming a transparent brittle resin which becomes extremely hard as the heating is continued.

It the process is interrupted at a point Where the product is a "liquid containing about 15-30% non-volatile, the unpolymerized material may be distilled off and re polymerized, leaving an oily residue which is a liquid and 100% non-volatile at 100 and ordinary pressure. This new synthetic drying oil is still unsaturated and will absorb oxygen and halogens, the rapidity of oxygen and bromine absorption being greater, the

lower the degree of polymerization.

, The essential features of this invention are disclosed in the following examples. It will be understood that these examples are furnished merely by way of illustration and that the conditions therein disclosed are susceptible to wide variation.

Ewamplc I One hundred parts bf 1i uid vinylacetylene are sealed in a closed tu e at 1 0 together with an equal volume of air (gaseous) and the system heated at 80-901for 15 hours. Upon opening the tube and distilling oil the unpol merized material a substantially 100 10-12% of the product remains as a thick, viscous, straw-colored oil. This material is soluble in benzene; rapidly absorbs bromine, rapidly oxidizes with air or other oxidizing agents, and reacts with ammoniacal cuprous copper or silver salts to yield typical acetylides. It cannot be distilled under any known conditions of temperature and pressure which will not result in decomposition.

E wample I 1 Example I maybe repeated, extending the volatile viscous product of Example I on distillation at 100 C.

\ Em pze III Exam le I may be repeated, but carrying Example I 7' Emample V Example IV may be repeated addition of 1% of benzoyl peroxide, giving 25-30% of nonwolatile polymer.

but with the thus Example l il' Gaseous vinylacetylene is dissolved in an equimoleeular quantity of cold toluene and then heated at 100-110 for 0 hours under an atmosphere of nitrogen giving less than 46% olf benzene soluble polymer.

Emample VII Example V1 is repeated only at a temperature oflEiO giving 20-30% of benzene soluble polymer in '2 hours.

Example VIII Vinylacetylene containing 1% er benzoyl eroxide is introduced into a nickel coil, 60 est long and held at a temperature of under a pressure equivalent to the vapor pressure of the mixture, namely 10-20 atmospheres, and at such a rate that it travels the len h of the coil in 5-6 hours; the material removedfrom the other end of the coil as fresh vinylacet lene is introduced, being continuously disti led and the recovered vinylacetylene being returned to storage for introduction into the tube again. In this manner, 20-25% of the vinylacetylene is converted into the liquid polymer per cycle through the coil.

Example 1X In the manner of Example V vinylacetylene is heated for 6 hours in a closed system with 1% of'manganese dioxide at 110 giving 15-20% polymerization.

.Ewample X Example IX is repeated replacing the manganese dioxide with sodium perborate,

thus producing approximately 12-15% of polymer.

Ewample XI A solution containing one part of vinyl it travels the length of the coil in 5-6 hours the material removed from the other end the coil as fresh vinylacetylene is introduced,

being continuously distilled, and the recov- 0 ered vinylacetylene returned to storage for introduction into the tube again. In this manner 40-50% of .the vinylacetylene is converted into polymer per'cycle through the coil.

' Concerning the boiling point of the prodnot of Example XI, the thick viscous oil re-- sulting is essentially non-volatile. If it were subjected to the process of distillation, a very small quantity might distil at an indefinite temperature substantially above 100; under 9 conditions of verylowpressure,asecondsmall quantity of material might be distilled off at an indefinite temperature, leaving the great majority of the product, somewhat more viscous as a result of this distillation but in 9 itself, non-volatile under any known conditions of temperature and pressure which will not result in decomposition of the product.

The following examples disclose the preparation of the gelatinous and solid polymers of vinylacetylene discussed above.

Example XII One hundred parts of liquidvinylacetylene are sealed in a closed tube together with 1 5 part of benzoyl peroxide and the mixture heated for hours at 110 Upon opening the tube at the end of this period, the product is found to be light yellow colored, gelatinous polymer, of which a small portion 0 is soluble in benzene. This semi-solid material is characteristii'ally unsaturated,-absorbing oxygen from the air, reacting with halogens and violently charring when treated with strong sulfuric acid.

EwampZe XIII other strong oxidizing agents, and similarly,

it has been found to slowly burn in air with the formation ofheavy depdsits of carbon.

It will be obvious from the above examples 5 that the polymerized products may be obsolid polymer is relatively inert; it does not corrosive chemical agents; It is slowly oxi dized by treatment withstrong nitric acid or.

sures above atmospheric facilitate polymerization of the vinylacetylene but are not-essential. Although its rate of polymerization at temperatures below its boiling point is extremely slow and, since the boiling point is substantially below ordinary temperatures, if stored at room temperatures, it must be kept under pressure. The degree of heating may be varied over a wide range; temperatures as low as room temperature will result in avery slow polymerization, 10-13% of polymer being formed in 4-6 months time. Increase of temperature results in a very marked increase in the rate of polymerization, thus temperatures between and 200 have been found useful, though great care should be exercised in operating at temperatures above 110, for the danger of explosion is very great. For this reason, we prefer the temperature ra ge between and 110 in the absence of a solvent.

Polymerization catalysts may or may not be used, as desired. As catalysts for this polymerization, the following materials and groups of substances have, for example, been found effective alkali metals, such as lithium,

certain metals such as aluminum chloride,

zinc chloride and cuprous chloride; halides of non-metals and metalloids such as stannous an rl stannic chloride, antimony triand pentachloride, arsenic triand pentachloride, 'sulfur monochloride titanium tetrachloride, boron fluoride etc.; certain acids such as sul furic acid, phosphoric acid, chlorosulfuric acid, fluoroboric aci and formic acid; oxygen; peroxides such as sodium peroxide, barium-peroxide, manganese dioxide, hydrogen peroxide, and benzoyl peroxide; percarbonates, perborates, persulfates and other persalts; anhydrides such as acetic anhydride, maleic anhydride and phthalic anhydride. The rate of polymerization in each of these cases is proportional to the quantity of catalyst used, each catalyst being different in regard to the quantity necessary to pro- 1 to accelerate polymerization other than the previously disclosed Nieuwland catalyst which as already explained is not adapted to the purposes of this invention.

Vinylacetylene and its polymers absorb oxygen upon exposure to air and the oxygen so absorbed acts catalytically in the process l lO of polymerization. This avoided by carrying out the polymerization in the absence of air, for example, under-an atmosphere of nitrogen. If allowed complete access to air, the polymerization is rapid and the tendency to become semi-solid or gel-like becomes greater; thus in an atmos ere of nitrogen, the products may be stored or many months at room temperature, whereas in air, polymerization and oxidation will cause gel ling at room temperature in several days. Further, excessive oxidation may result in the formation of explosive oxides, hence the use of oxygen and peroxidesas catalysts must be limited to small amounts.

The polymerization may or may not be carried out in solution as desired. 'The follow ing solvents, for. example, have been found valuable under various conditions of operation: acetic acid, methyl alcohol, ethyl alcohol, propylalcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, acetone, methyl acetate, ethylacetate, propyl acetate, butyl acetate, methyl butyrate, ethyl butyrate, butyl butyrate, other esters of low molecular weight, solvent naphtha, benzene, xylene, toluene, 'tetrahydronaphthalene, decahydronaphthalene, cyclohexane, cyclohexanol, methylcycylohexane, pentane, hexane, heptane, octane, and other saturated hydrocarbons. The aromatic hydrocarbon solvents such as toluene, xylene and solvent naphtha are among the preferred solvents.

The amount of solvent employed may be varied without limit. In general, however, concentrations of from 10 to 80% of vinylacetylene (by weight) are ,used. Since the presence of a, solvent acts to slow down the polymerization, the rate of the reaction may be conveniently controlled by the addition of may, if desired, be

the solvent in appropriate quantities. 'When' the polymerization is thus controlled, the danger of the formation of excessive quantitt'es of the less desirable higher polymers is greatly diminished. In the event that a solvent is used, higher temperatures may -also be used with safety, for the va or pressure of the system may be decrease and the danger of spontaneous decomposition of the acetylene compound greatly reduced. In this manner, temperatures up to 200 have been successfully used, although temperatures between about 80 and 150 C. are ppeferred. By means of such temperatures the retarding .efiect of the solvent may be overbalanced and the process even speeded up.

As will be evident from the examples, various methods may be used for carrying out the polymerization. First, gaseous vinylacetylene may be dissolved in a cold liquid solvent, enclosed in an air-tight system and heated, thus accomplishing the polymerization directly in the solvent. Second, it may be liquefied and enclosed in an air-tight con-,

,tainer either with or without a solvent and polymerize and then al by distilreturning it to the polymerizer. In

in preparing the viscous liquid this manner, the formation of solid gelatin- I ous products is avoided and a polymer of muchhigher solubility is obtained. owever, in the case of polymerization in solution, the degree of polymerization may be carried much higher than in the absence of a solvent. Thus, where a sample of pure vinylacetylene may gel when it is polymerized to the extent of 30%, a 50% solution of vinylacetylene in toluene may be polymerized until over of the available vinylacetylene is in the form of polymers without gelling. The preferred degree of polymerization lies between 10 to 30% polymerization in the case of straight vinylacetylene and 10 to in the case of viriylacetylene in solution. egardless of the particular process the resulting products alldiifer from the products obtainable from known hydrocarbons by polymerization in that they are more highly unsaturated and absorb oxygen in the manner of bodied drying oils. Thus, the liquid nonvolatile polymers constitutea new class of synthetic drying oils suitable for compounding as paints and lacquers. -After drying in air, the films formed by these polymers are highly resistant to chemical action. In most illustrated in the Nieuwland case, Serial No. 330,415,'but are lighter in color and softer and the liquids on standing furnish films displa ing greater toughness, better adhesion an greater light stability than those obtained by the polymerization of divinylacetylene or of mixtures containing the same. These products are, therefore, new composi 'tions of matter consisting of polymers of vinylacetylene in substantially pure form and possessing acetylenic side chains, namely side chains composed ofithe group C x p It is not the intention toclaim herein prod? ucts resulting from cross polymerization or from simultaneous polymerization of vinylacetylene with other polymerizable substances. As many apparent and widely different embodiments of this invention may be made without departing from the spirit thereof, it is to be understood that we do not limit ourselves to- 'the foregoing examples or deing claims.

respects the products are comparable to those scriptions except as indicated in the follow- 'ize ing from heating substantially pure vinyl heating substantially pure vinylacetylene and varying from a transpa nt liquid-soluble in alcohol, acetone and b zene, to a transparent, hard brittle resin substantially insoluble in said solvents.

4. A substantially pure polymer of vinylacetylene obtainable by heating the same in a closedtube with 1 part of benzoyl peroxide for 20 hours at 110 (3., said product beingpartially soluble in benzene, of a semi-solid gelatinous consistency and adapted to harden on exposure to air.

5. A substantially ure polymer of vinylacetylene obtainable y heating the same in a closed tube with 1 part of benzoyl peroxide for 200 hours at 110 0., said productbeing ahard, brittle solid, insoluble in benzene.

6. A viscous non-volatile liquid polymerization product of pure vinylacetylene soluble in benzene, adapted toharden on, exposure to air and yielding acetylides when reacted with ammoniacal cuprous copper.

7 A liquid polymerization product of pure vinglacetylene, said polymer to a degree corresponding to t at resultacetylene in a closed vessel and in the presence of an equal volume of air at a tempera ture of from 80 to 90 C. for 15 to 30 hours.

8. A substantially pure polymer of vinylacetylene obtainable by heating the same in pure form in a closed vessel without access of air for from 5 to 6 hours at a temperature of from 100 to 110 C. and thereafter removing those roducts boiling at or below 100 C.

9. liquid hydrocarbon obtainable by mixing 1 part of substantially pure vinylacetylene with 0.005 parts of benzoyl peroxide and 1 part of toluene and exposing the mixture in athin stream and in the absence of air to a temperature of 120 C. and a pressure of 10 to 15 atmospheres for 5 or 6 hours and removing from the resulting product those products boiling at or. below 100 C., said hydrocarbon being soluble in benzene, adapted to oxidize on standing in air and reacting with ammoniacal cuprous copper to yield acetylides.

10. the process of producin hydrocarbons of higher molecular weight rom monovinylacetylene, the step which comprises polymerizing vinylacetylene in the absence of other polymerizable substances.

In the process of producing hydrocar- 3 A hydrocarbon product obtainableby ein polymer- 1 bons of higher molecular weight from monoof air and in the absence of other po ymerizable substances.

- 12. In the process of producing hydrocarbons of hi her molecular weight from monovinylacety lene, the step which comprises polymerizing vinylacetylene in the absence of air and other polymerizable substances.

13. The process of producing hydrocarbons which comprises heating vinylacetylene to a temperature of from 25 to 200 C. and in the absence of other polymerizable substances.

14. The process of producing hydrocarbons which comprises heating -.vinylacetylene in the presence of an inert solvent and in the absence of other polymerizable substances.

15. The process of producing non-benzenoid hydrocarbons which comprises heating vinylacetylene to from 50 to 150 C. in the presence of a polymerization catalyst other than a cuprous chloride, ammonium salt solution and in the absence of other polymerizable substances.

. 16. The process of producing an unsaturated hydrocarbon from vinylacetylene which comprises heating the vinylacetylene in the absence of other polymerizable substances to a vinylacetylene is heated in a closed vessel in the presence of air to eflect polymerization of at least 10% of the vin lacetylene to products boiling above 100 18. The process of claim 16 in which the vinylacetylene is heated to a temperature between 50 and 110 C. in a closed vessel and in the absence of a solvent until between 10% and 30% of the vinylacetylene hasbeen polymerized to products boiling above 100 C.

19. The process of producing a polymer of vinylacetylene in, which the vinylacetylene is heated in the absence of air and 1n the presence of an inert solvent to effect polymerization of from 10 to of the vinylacetylene to a non-volatile product.

20. The process of claim 11 in which the vinylacetylene is heated in the presence of substantially 20% to 90% of its weight of an aromatic hydrocarbon solvent until between 10 and 95% of the .vinylacet lene has been polymerized to products boiling above C.

21. The process of claim 11in which the vinylacetylene is heated to a temperature of in otherwise pure form, together with an aromatic hydrocarbon solvent and a catalyst "is continuously passed through a coil heated to a temperature below 200 C. to effect partial polymerization of the vinylacetylene to nonvolatile products, continuously separating the non-volatile products from the mixture discharged from the coil and reintroducing the volatile products with the fresh vinylacetylene into the coil. i

23. .The process of claim 20 in which the degree of polymerization of the liquid corre sponds to that obtainable by exposm 1 part of vinylacetylene with 0.005v Parts of nzoyl peroxide and 1 part of to uene in a thm stream inthe absence of air to a temperature of from 80 to 150 C. for from 5 .to 6 hours.

In testimony whereof we aflix our signatures.

ALBERT S. CARTER. FREDERICK B. DOWNING. 

